Improved the docs

docs/heuristics.md

@@ -50,7 +50,7 @@ The evaluation features are used in several classes.
 
 ## Evaluation Function
 
-[Chess\EvalArray](https://github.com/chesslablab/php-chess/blob/main/tests/unit/EvalArrayTest.php) allows to transform a FEN position to decimal numbers between -1 and +1. -1 is the best possible evaluation for Black and +1 the best possible evaluation for White. Both forces being set to 0 means they're balanced.
+[Chess\EvalArray](https://github.com/chesslablab/php-chess/blob/main/tests/unit/EvalArrayTest.php) allows to transform a FEN position to numbers between -1 and +1. -1 is the best possible evaluation for Black and +1 the best possible evaluation for White. Both forces being set to 0 means they're balanced.
 
 ```php
 use Chess\EvalArray;
@@ -149,7 +149,30 @@ Array
 )
 ```
 
-The relative value of a position in FEN format without considering checkmate can be obtained by adding the above values.
+As chess champion William Steinitz pointed out, a strong position can be created by accumulating small advantages. The relative value of the position without considering checkmate is obtained by counting the advantages in the evaluation array.
+
+```php
+use Chess\EvalArray;
+use Chess\FenToBoardFactory;
+use Chess\Function\CompleteFunction;
+
+$fen = 'rnbqkb1r/p1pp1ppp/1p2pn2/8/2PP4/2N2N2/PP2PPPP/R1BQKB1R b KQkq -';
+
+$board = FenToBoardFactory::create($fen);
+
+$normd = EvalArray::normalization(new CompleteFunction(), $board);
+$count = EvalArray::count($normd);
+
+echo $count;
+```
+
+```text
+1
+```
+
+In this example, one evaluation feature is favoring White.
+
+An alternative way to look at it is to add up the values ​​in the evaluation array.
 
 ```php
 use Chess\EvalArray;
@@ -169,7 +192,7 @@ echo $sum;
 0.24
 ```
 
-In this example, White is slightly better than Black because the value obtained is a positive number.
+White is slightly better than Black because the value obtained is a positive number.
 
 This is an estimate that suggests who may be better without considering checkmate. Please note that a heuristic evaluation is not the same thing as a chess calculation. Heuristic evaluations are often correct but may fail because they are based on probabilities.